Chuck and Ryan's Build Tips

[ceslaw]

I have been posting construction tips over at Supercub.org, but since it is about a Carbon Cub, this seems like a better place to post. So I will be posting future tips and thoughts on this site.

Floor board

When the floorboard is finally set in place one feels like some real progress is being made. But before setting that floorboard in place here some tips.

There are some 40 holes pre drilled and tapped in the frame for screws to secure the floor board. But odds are the threads are a bit rusty or have a bit of powder coat on them which will make screwing problematic. So get out a tap and run it through the holes before the floor board is set in place.

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We used the Boelube with the tap. Good stuff. A piece of tape on the tap let us know when we had gone in far enough. After each hole was tapped it was marked with a silver Sharpee so we could keep track of what we were doing.

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The screws went in easily thanks to this little extra step.

We also sprayed a bit of Corrosion X into each of the threaded holes. This is pretty neat stuff we picked up at EAA Air Adventure a couple of years ago. It is a rust preventer that comes out like a foamy oil but clings to the steel. It works well on raw steel surfaces, like a drill press table.

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The manual describes pre-installing the pedals before the floorboard is set in place. The pedals have screws that go directly into the frame (two on each front, one on each rear), so preinstalling them could create an issue with aligning them once the floor is in place. We simply installed the floor board and then set the pedals in place. Initially all the screws are just put in with a couple of turns and then once they are all set in place tightened. (We used a battery drill with the torque preset to assure uniform tension). Finally the pedal screws that go through the floor board with backing washers and nuts were added. There were no alignment problems using this approach.

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[c130jake]

Great idea.

[Pete D]

These holes are flow drilled and roll tapped. It would be best to use a roll tap, not a standard cutting tap to chase these holes.

[ceslaw]

These holes are flow drilled and roll tapped. It would be best to use a roll tap, not a standard cutting tap to chase these holes.

Thanks Pete. It is good to know the pros are keeping an eye on us builders. Good point!

I should have noted in my post:

1. Just the tip of the tap was used to clean out the top threads and the tap was never "forced".

2. The green tape visible in the pictures was a marker to make sure the tap only went in a short distance.

3. The screws were still snug, but easier to start once the first few threads were chased.

But your point is well taken. Thanks.

[ceslaw]

Cup Holder Update

Last November I posted that my order for a Carbon Cub EX was placed just days after Cubcrafters revealed that the 2014 model would include a cup holder; clearly a factor in making such a big purchase decision. In June I posted what are believed the first public photos of the elusive cup holder. And now I can reveal yet another cup holder update.

While at Oshkosh Cubccrafters was touting their official beverage container. It is an impressive vessel which has a full frontal view of a Cub and is made in the USA. This is a necessity for any serious Cub pilot, so I brought one home. Upon returning home I was able to confirm that it fits perfectly in the carbon fiber kick panel cup holder. Kudos to the CC engineering department for yet another fine addition to their product line.

[ceslaw]

Boot Cowl

1. Before any rivets are placed on the fire wall, we used the fire wall as a pattern to cut out the black vinyl and fiberglass insulation. We used the fire wall as a pattern to cut out each of the holes with a #11 Exacto knife.

Per Mitch, the holes in the vinyl and insulation that carry the engine mount bolts need to be enlarged to assure the metal fire wall will directly contact the frame.

Once all the holes are neatly cut, we glued the vinyl to the fiberglass with 3M spray adhesive. Then we set it aside. The fire wall was also used as a pattern to mark an outline on a 4 x 4 section of birch veneer plywood.

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2. We measured 1 ¼ to 1 ½ inches inside the outline of the fire wall on the board so there would be enough space to clear the out squeeze riveter and then we cut it out. Even cutting it back that distance proved insufficient and we ended up grinding a bit off the rivet squeezer.

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3. When placing the fire wall / plywood on the fuselage we discovered that the top of the heater vent on the floor board was interfering. It was trimmed back even with the fire wall. Four hardware store 5/16” bolts were used to hold it in place, ready to add the side panels.

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4. The temporary instrument panel was installed with those frustrating Adel clamps per the award winning Mitch Travis video. We discovered that the lateral position of the panel is important and can make a difference in the way the support tubes center in the openings. The holes for mounting the panel were elongated so that we could precisely locate it evenly left to right, marking a reference point and then measuring on both sides. A tiny lateral variation in the location of the panel can make a difference in the alignment of the two support tubes in the cowl openings.

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5. Use lots of clips. We placed a clip between every rivet hole. Start the clips at the bottom so that the angle at the bottom of the cowl is exactly even with where the tunnel will be. Odds are by the time you get done working your way to the top with those clips the top center seam will come together nicely. Likewise when placing the spacer strips, start at the bottom at the angle. This will result in a better fit at the bottom.

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6. The gascolator cover went together just fine until we went to place the six Tinnerman nuts. None fit. On Mitch’s award winning video the Tinnerman nuts referenced were part number A1785-6Z-1D. Those are also shown in the pictures in the manual, although the manual references part number A1784-6Z-1 which is what came with the kit. So we called Wick’s and spent three bucks for the longer A1785-6Z-1D nuts, which worked just fine. Alternatively one could notch out the panel a bit so the supplied nuts would fit. I admit it. I’m lazy.

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[ceslaw]

Fuel Lines

1. After setting the fuel lines in place, test fit the forward left and right interior panels. They have cut outs for the fuel line supports and you will know if you got the supports in the correct location while they can still easily be relocated.

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2. Protective hose about an inch long is supposed to be slid on to the fuel line to protect the line when the plastic ties are pulled tight. Yea, sure. Sliding a section of that covering line a few feet is like pulling up a 50 pound boat anchor without a windlass. Once the one inch pieces were cut we simply split one side length wise and snapped it over the desired location, then taped the ends with friction tape to hold it in place per the manual.

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3. We checked for leaks per the updated on line manual: using a bit of compressed air and soapy leak tester. BORING. Did not find any evidence of leaks and had a soapy mess on all the joints. I much prefer the balloon technique, which I have now refined to a fine art since an earlier post.

First, the fuel tank lines on the left side were connected with a section of 3/8” hose. The clamps have to be really tightened down to prevent any slow leaks.

Second, a balloon is placed on the right side, aft tank line. This is the most distant point from the gascolator. I placed a short section of 3/8 hose and put the balloon opening over that hose to assure a tighter fit. Electrical tape made a good seal around the balloon.

Third, the aft drain was sealed with a threaded plug. The forward drain and the right forward fuel tank lines were sealed with a bolt, section of hose, and hose clamps. This left only the gascolator line open.

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Fourth, a balloon was inflated and taped on the fuselage as a ‘control’. Finally, the balloon on the aft right fuel tank line was inflated by blowing through the only open line to the gascolator (No compressor necessary!) After the balloon was inflated it was sealed with a section of hose, bolt, and clamps.

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Now the hard part. Waiting. I set this up a several days ago and both the control and test balloon are still inflated. I am much more confident that the system is leak free with these balloons than with the silly soapy mess.

[Lloyd]

Regarding sliding the protective tubing over the fuel line, I had the same experience. Hard as heck to go much more than a few inches. Chuck's solution is simple and a good alternative. I found by chance that the cut off portion of the bottom stringer exactly fits over the fuel line and makes a good pusher for sliding the protective tubing on. The difficulty lies with figuring out how many pieces of tubing to slide on and their relative position. They can be slid a little bit once in close position. When I missed one, after all the others were in place and tied down, I slit the tubing as Chuck did.

[ceslaw]

Stringers

It took me about 12 hours to install the carbon fiber stringers which I suspect is longer than most.

1. Temporarily set them in place using clamps. The 1” clamps work well. This is the time to work on the alignment.

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2. The left long stringer was the most challenging, with a noticeable gap between the stringer pad and the frame at the transition from the cabin to the baggage area. While at Oshkosh Mitch told us that it is okay to leave a gap and simply fill in the space with methocrylate up to a quarter inch or so. (We had originally glued it down tight, but after talking to Mitch we popped it off and re-glued it so it would be tension free. The manual on line has been updated to reflect this point).

3. If you have the extended baggage option, Do NOT glue the upper stringer on the right side at this time. That stringer lines up with the bottom of the baggage door frame. It is MUCH easier to install the door frame and then fit and install the stringer.

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4. Take a sanding block and run it down the outer portion of the stringer, keeping the sanding block perpendicular. This will create a 1/8” line that will make it easier to eyeball the stringers to make sure they are straight.

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5. Once satisfied with the location of the stringers, use a silver Sharpie to place a mark on the frame around the glue pads and a short straight reference line. This will make it much easier to align it exactly when the glue is applied. Remove the stringer and then rough up the powder coat within the area you just marked with a Scotch Brite pad.

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6. Use a bungee strap to hold the leading end and aft end of each stringer in place when starting to glue. This makes it easier to pull the stringer away to place the glue. Starting at the aft end, clamp where needed once the glue is applied.

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7. I set up both the stringer and blocks on the bottom of the fuselage and the side stringers and glued them in the same session to minimize waste of methocrylate.

8. Denatured alcohol works well to remove unwanted drips and streaks of methocryate.

9. When finished, open the windows and doors, let that nasty smelling stuff dry, and take the rest of the day off. I waited 24 hours before removing the clamps.

[ceslaw]

Boot Cowl, Follow Up

As noted in our Boot Cowl post, Mitch suggested that when cutting the holes in the vinyl and insulation panel, the four holes for the engine mount should be enlarged to assure the fire wall would be in direct contact with the frame. We used a 1 ½ inch washer as a pattern.

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